Yoga

Does it work?

Systematic reviews, meta-analyses

Ten systematic reviews of yoga in cancer have been published, 9 of which included between 6 and 18 randomised controlled trials (and a total of 313 to 905 patients).22-29, 37-38 The reviews are described in table 1. Differences in the number of included studies reflect differences in the inclusion criteria, whether trials were restricted to certain types of cancer and the range of outcomes covered. The date of the searches also affected the number of trials located. One recent review searched only for studies published between January 2010 and July 2012 and included a range of study types 29 while one, which focused solely on patients with haematological malignancies, included only one small trial.37

Breast cancer

Systematic reviews of yoga in breast cancer address a wide range of outcomes. These reviews demonstrate evidence of a significant but possibly short-term beneficial effect on quality of life and evidence of a small beneficial effect on well-being, with the evidence described as moderate to good for both outcomes.22,24,25,27,28 One systematic review concluded that the effect size for improved psychosocial outcomes was moderate to large.22 Conclusions on the evidence were conflicting with regard to the effects of yoga on sleep and psychological health while recent trials of fatigue have been more positive than older trials.22,23,24,26-28, 37. Effects on physical function were not found to be significant.22 The evidence also indicated that effects were limited to the active treatment phase.24 The quality of the included trials varied considerably. There is also potential for the introduction of bias particularly when subjective outcomes are assessed by patients as masking of treatment is impossible and selecting appropriate control interventions is difficult.

Haematological malignancies

A Cochrane review found only one small trial in 39 people with Hodgkin or non-Hodgkin's lymphoma. 38 This trial compared Tibetan yoga plus standard care against standard care alone. Beneficial effects on sleep were reported but the risk of bias was assessed as high.

Other cancers

Only three RCTs in patients with other types of cancer were included in the systematic reviews, one small trial in lymphoma patients as described above and two in mixed cancer types. In the two trials in mixed cancer, yoga was part of a mindfulness programme.25

Summary of effects by outcome (see Table 3)

Anxiety: Positive effects are reported on anxiety but results are heterogeneous and only positive in the short-term when yoga is compared with active controls rather than no treatment.

Depression: Positive effects are seen in depression in the short-term but results are heterogeneous.

Distress: Reports of effects on distress are mixed with more positive results reported when yoga is compared with active controls than no treatment controls.

Fatigue: Recent trials have reported more positive results than older studies leading to overall positive effects being reported for fatigue.

Perceived stress: Positive effects are seen on perceived stress in the short-term but not the long-term.

Physical health: Significant effects on physical health are not reported.

Quality of life: Overall, effects in quality of life are positive.

Sleep problems: Few trials have reported effects on sleep leading to overall non-significant results although positive effects are reported in one trial in lymphoma patients.

Wellbeing: Positive effects are reported on various aspects of wellbeing except in mental wellbeing when yoga is compared against no treatment.

Randomised controlled trials

Eight RCTs have been published since the most recent systematic review (see table 2).39-46 Of these, 7 were in breast cancer patients 39-44, 46 and one included mainly breast cancer patients. 45 A range of outcomes have been assessed including psychological responses, physiological markers of stress and inflammation, effects on lymphoedema and impact on overall quality of life. While some trials used appropriate methods for randomisation and allocation concealment, reducing bias to some extent, blinding of patients is not possible with interventions such as yoga. In most cases the control group received no treatment so there is no control for non-specific effects but there is some support for positive results from effects observed on physiological measures. However, interpretation of the results is complicated by varied interventions and differences in delivery (through classes, home practice and a combination of both of these). A further issue affecting implications for practice is that high attrition from yoga groups is a problem.

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